DNG’s typically (but not always) have two color matrixes, one at D50, and one at D65
@RTCharles that part is incorrect. Most of the time the StdA illuminant is set as illuminant 1 and D65 as illuminant 2. While is it legal according to the DNG specification (v1.4.0.0, page 31) for D50 and D65 to be specified, I have never seen that, and it would not make much sense.
Agreed that a raw converter should check and not assume - I don’t currently know whether RT does that.